Face to face, pos ??? Help stumped!!

One of our Medicare patient is residing at rehab and the rehab brought the patient to our office. We billed an office visit. At first it paid, then they denied stating patient is an inpatient. Come to find out, this patient is registered as inpatient. So I billed POS 61 to show the patient's is in rehab facility but still denied. I received this information from PUB. 100-04 Medicare Claims Processing Manual, Chapter 26, Section 10.5. I am not sure what I am doing wrong. Does anyone know how to bill this scenerio?
Thanks!

re: FACE TO FACE, POS ??? HELP STUMPED!!

when you first billed it, did you bill POS as 21? My understanding is that if the provider saw the patient at the rehab, then it should be billed with POS as 61. Your facility is not listed as a rehab center per your tax ID. So if the patient was brought into a providers office and was seen there I would think it would be billed at the POS 21. You did not provide services at the rehab. Also if they want it billed as inpatient, are you using the correct CPT® code, maybe you should be using Transitional Care Mangement Services 99495-99496, just a thought:)